INSTR - DualBrain/bsharp GitHub Wiki

To search for the first occurrence of string y$ in x$, and return the position at which the string is found.

Syntax

INSTR([n,] x$, y$)

Comments

Optional offset n sets the position for starting the search. The default value for n is 1. If n equals 0, the error message Illegal argument in line number is returned. n must be within the range of 1 to 255. If n is out of this range, an Illegal Function Call error is returned.

INSTR returns 0 if:

• n > LEN(x$)
• x$ is null
• y$ cannot be found

If y$ is null, INSTR returns n.

x$ and y$ may be string variables, string expressions, or string literals.

10 X$ = "ABCDEBXYZ"
20 Y$ = "B"
30 PRINT INSTR(X$, Y$); INSTR(4, X$, Y$)

The interpreter searches the string "ABCDFBXYZ" and finds the first occurrence of the character B at position 2 in the string. It then starts another search at position 4 (D) and finds the second match at position 6 (B).